I like Olivia and Lucy together but do not like Livy and Lucy. That is a little to close for me. But if it does not bother you and your partner then go for it. Or maybe use the nn Olive instead of Liv/Livy. Olive and Lucy sound adorable. As for the name I can picture it on a baby, little girl and adult. I think it ages very well.

I agree with some of the others--Olivia and Lucy are fine (quite cute, in fact), but Livy and Lucy are probably too close. Maybe Livy and Lou/Livy and Lulu? I think if they weren't always Livy and Lucy, it would help.